Dissociation and Interoception in FND
By Susannah Pick et al
What is dissociation?
Dissociation is a loss of integration between neurocognitive processes that are usually integrated. It can involve altered experiences of self (e.g., detachment, emotional numbing, loss of memory for daily events), environment (e.g., things seeming dreamlike or unreal) and body (e.g., reduced sensation or control of body parts, out of-body experiences). Dissociation can be mild and is experienced by most people occasionally, but these experiences can be severe and/or occur very frequently for others, and this can cause significant disruption or distress in a person’s daily life. Dissociation is likely to arise from structural and/or functional alterations in brain networks involved in awareness of the self and body, cognitive control, and emotional processing (Krause-Utz et al., 2017; Perez et al., 2017; van der Kruijs, 2012; 2014).
What has dissociation got to do with FND?
Research has shown that dissociative experiences are often reported by people with FND, both in daily life and around the time of symptom occurrence (e.g., Hendrickson et al., 2015; Pick, Mellers & Goldstein, 2017). Several experts have proposed that dissociation might be an important part of explaining how FND symptoms occur (i.e., a ‘mechanism’). However, there have been few experimental, laboratory-based studies to test this hypothesis. So, the overall aim of this study was to examine the idea that dissociation might contribute directly to the occurrence of FND symptoms. To do this, we explored whether dissociative states affected bodily awareness (i.e., interoception) in people with FND, using carefully controlled, laboratory- based measures. We also wanted to assess whether dissociation had an impact on the confidence that participants had in their bodily awareness.
How was the study carried out?
We measured dissociation as it happened in the laboratory with a well-known measure (Clinician- Administered Dissociative States Scale), before and after a short procedure that induces mild dissociation in non-clinical participants (Shin, Goldstein & Pick, 2018). The procedure involved ten- minutes of ‘mirror-gazing’ in a dimly lit room, with a researcher present throughout. We also tested accuracy and confidence in bodily awareness (interoception) before and after mirror- gazing, with an established task (heart-beat tracking). We included an almost identical control task which assessed shape counting. Participants also completed a questionnaire about their bodily awareness in daily life (Multidimensional Assessment of Interoceptive Awareness, MAIA). We compared a group of 20 participants with FND to a group of 20 non-clinical participants (i.e., individuals with no major physical or mental health diagnosis).
What were the key results?
FND participants reported greater dissociation than controls before and after mirror-gazing, but the difference was greater afterwards.
The FND group had good accuracy on the bodily awareness task before mirror-gazing, but showed reduced accuracy afterwards, compared to controls. In contrast, the FND group performed well on the shape-counting control task at both time points.
Interestingly, FND participants reported lower confidence in both bodily awareness and shape- counting at both time points, regardless of performance.
On the MAIA, FND participants reported that in daily life, they were more likely to use distraction from unpleasant bodily experiences and perceived their bodies as less safe and trustworthy, compared to controls.
Conclusions and significance
The findings suggested that dissociation is potentially a significant difficulty for many people with FND and that dissociation-inducing situations may trigger or lead to worsening of FND symptoms. Dissociation may therefore be an important mechanism and treatment target. As the FND group seemed to underestimate their cognitive abilities in this study, this could be viewed as a difficulty with ‘metacognition’, which refers to the ability to accurately monitor and assess one’s own cognitive processes. It is unclear whether this is a cause or consequence of having
Similarly, the self-reported use of distraction from bodily sensations and reduced bodily trusting could contribute to the development of FND symptoms but could also be a consequence of living with FND.
More research is needed on dissociation, interoception and metacognition in this group, particularly in how these processes relate to symptom occurrence/severity and brain structure/function.